This invention relates to gas turbine engines used for powering aircraft, and more particularly for such engines employed for aircraft intended to operate at speeds ranging from subsonic to supersonic.
Engines having the ability to operate effectively over a range of speed from subsonic to supersonic may include an augmentor or afterburner for providing thrust augmentation for take-off, some maneuvers and for supersonic acceleration. Such engines further may include a variable area bypass injector that provides improved engine performance.
Optimum operation of such engines over the wide range of conditions occurring from subsonic speed to supersonic speed requires satisfying demanding criteria. For example, it is desirable, particularly during dry or non-augmented operation, that the core gases and the bypass gases by mixed as uniformly as possible before discharge from the exhaust nozzle of the engine. It is also desirable to hold the engine airflow, which is affected by the fan employed in such engines, by the speed of the aircraft, and by the engine thrust requirement, in order to operate at an optimum point on the performance map of the aircraft. It is necessary that a satisfactory flameholder be provided to maintain the flame supplying heat to the augmentor, despite the high speed of airflow through the fuel-burning area. Further, it is desirable that the spraybars or fuel tubes providing fuel for the augmentor not be subjected to too high a temperature because under such conditions the fuel may decompose and the resultant deposits may plug holes, which may be as small as 0.020-0.040 inch, in the fuel delivery system. The engine of the subject invention is designed to meet all of these demanding criteria with resultant optimization of the performance of the aircraft.
Prior art engines have included augmentors, provision for mixing core gases and bypass gas, and have provided flameholders for the fuel burning elements. However, no prior art of which the applicants are aware has incorporated in a single structure, as in the subject invention, provision for supplying fuel, for flameholding, for cooling the spraybars through which the fuel is supplied, for actively controlling, or modulating the area through which bypass gases are injected into the core gases being exhausted from the core engine, and for effecting a thorough and complete mixing of the core gases and bypass gases before discharge through the exhaust nozzle of the engine.
Accordingly, it is an object of this invention to provide, in a single combined structure, means for effecting thorough mixing of bypass gas and core gases over substantially the entire area of the exhaust passage of the engine, for incorporating in the structure fuel rods or spraybars and flameholders for the fuel being burned, for efficiently cooling the walls of the structure and components therein, including spraybars, support members, etc, for deswirling the core gases discharged from the core engine and for controlling the injection of bypass gas into the core gases.